Direct postive photogrpahic color process



1951 GE. FALLESEN EIAL 2,566,180

DIRECT POSITIVE. PHOTOGRAPHIC cdLoR PROCESS Filed Aug. 13. 1948 EXPOSUREINTERNAL mmvr/maz F] G. 1. 1 TREATMENT 04 com)? DEVELOPER aw: arm/11v:INH'RN/ll. EMULSION 22 q rc'uow FILTER 2o g}- GREENSEM'IT/Vf INTERNALEMULSION FIG. 2. RED SENSITIVE INTERN/IL EMULSION GEORGE E.FALLESENROBERT E. STAUFT'ER INk'jNTQRS M ATTORNEYS Patented Aug. 28, 1951 UNITEDSTATES PATENT OFFICE Rochester, N. Y., assignors to Eastman KodakCompany, Rchester, N. Y., a corporation of New Jersey ApplicationAugus't13, 1948, Serial No. 445214 3'C1aims. I This invention relates tophotography and particularly to a method of making direct positive colorphotographs.

Fallesen U. S. application Ser. No 780,405, filed October 17, 1947, nowU. S. Patent 2,497,875,

granted February 21, 1950, describes a process of making direct positivephotographs in which a special type of silver halide emulsion capable ofgiving an internal latent image is exposed and developed in aphotographic developer which is capable of giving aerial fog. Exposureof this emulsion produces an internal latent image and development ofthe exposed emulsion in a developer which gives aerial fog, develops apositive image inthose regions of the emulsion layer which were notexposed. Stauffer U. S. application Ser. No. 780,569, filed October 17,1847, now U. S. Patent 2,497,817, granted February 21, 1950,. describesa method for obtaining increased aerial fog and higher maximum densityof, the reversal image in the Fallesen process by the addition to thedeveloper of certain compounds such as benzotriazole which are soconstituted as to increase the maximum density of the positive imageobtained in developing solutions capable of producing aerial fog.

Glass and Richey, as described in their U. S. application Serial No.780,574; filed October 17, 1947,. now U. S. Patent 2,507,154, grantedMay 9, 1950, found that the aerial fogging developer of Fallesen couldbe replaced with a developer containing a primary aromatic aminodeveloping agent and an active methylene coupler compound to formpositive silver and dye images. In the Glass and Richey process theformation of the dye image is incidental to the formation of the silverimage, since not all color couplers produce the reversal obtained withthe active methylene coupler compounds. Couplers of the naphtholic orphenolic type are not operative in a the Glass and Richey process.Therefore, while yellow and magenta dye images can be obtained in theGlass and Richey process cyan images 1 have not been obtained and theprocess has limited utility in the field of color photography.

Ives described, in U. S. application Serial No.

capable of developing the surface latent image.

Since the processes described above are not capable of producing a rangeof colors suitable for natural color photography, it is the primarypurpose of our invention to provide a method for the production ofnaturalcolor images, that is, a methodwhich will permit the formation ofdirect positive color photographs having a full range ofcolors.

This object is accomplished according to our invention by following atwo-bath procedure similar to that of the Ives application'S'erial No.780,318, now Patent No. 2. 333 oh We expose a suitable single layer ormultidayer emulsion to an image, treat the exposedmaterial for a shorttime in a developer capable of producing surface latent ima e in theunexposed regions and then treat the exposed material in a developingsolution containing a primary aromatic amino developer. To produce acolor image, there must be a color coupler either in the developer or inthe emulsion layer and either method can be used according to ourinvention.

In the accompanying drawing, sectional views of a photographic elementat successive stages in our process are shown.

The photographic emulsion used in the process of our invention is agelatino-silver halide emulsion such as silver bromide, silverbromoiodide or silver chloroiodide emulsion. It need not contain opticalsensitizing dyes although certain sensitizing dyes may be added to itfor the purpose of inducing aerial l'o'g, as well as for opticalsensitizing The emulsion should be undigested or if digested, thedigestion should be carried out without the use of surface sensitizers.An emulsion of this type isknown as Burtons Emulsion described in WallPhotographic Emulsions, 1927, pages 52 and 53. A further type ofemulsion suitable for our process is an internal latent image emulsiondescribed in Davey and Knott U. 3. application Ser. No. 790,232, filedDecember 6, 1947, now abandoned, of which application Serial No. 82,914,filed March 22, 1949, is a continuation-in-part.

Most of the internal latent imagetemulsions are silver bromoiodide ofhigh iodide content, preferably containing at least 10 to 20% of theamount of silver halide as the iodide. Burtons Emulsion is an emulsionof. this type having a silver iodide content ofapproximately 40% of thecontent of silver halide. It is not absolutely essential, however, forthe emulsion to contain silver iodide.

An internal latent image type of silver hal- 3 ide emulsion may bedefined as one which, when a test portion is exposed to a lightintensity scale for a fixed time between ,5 and 1 second and developedfor 4 minutes at 20 C. in the ordinary surface developer (Example 1),exhibits a maximum density'not greater than the maximum density obtainedwhen the same emulsion is equally exposed and developed. for 3 minutesat 20 C. in an internal type developer (Example 2). Preferably themaximum density ob= tained with the surface developer is not great-= erthan 1 6 the maximum density obtained when the same emulsion isdeveloped in the internal type developer. Stated conversely, an internallatent image emulsion, when developed in an internal type developer(Example 2) exhibits a maximum density at least and preferably at least10 times the maximum density obtained when the emulsion is exposed inthe same way and developed in a surface developer (Exam= ple 1).

According to our method of producing direct positive color images, anemulsion of the type described above is exposed to light rays or to asuitable image and is then bathed for approximately seconds to 1 minutein a selectively fogging developer such as those described in FallesenU. S. Patent 2,497,875, Stauifer U. S. Patent 2,497,817 or Glass andBichey U. S. Patent 2,507,154. After a brief rinse, the film is placedin an active developer containing a primary aromatic amino developingagent and a color coupler, unless the color coupler is present in theemulsion layer. Color couplers of the proper constitution can beintroduced into the emulsion layers either in the form of coupler-=solvent dispersions as described in Marines and Godowsky U. S. Patent2,304,940 or Jelley and Vittum U. S. 2,322,027 or as non-wonderingcoupiers of the type described in Fischer U. S. Patent 1,102,028. Aboutten minutes are generally required to produce the color image, althougha shorter time may be sufficient. If the film is allowed to remain inthe selectively fogging developer for about 12 to 15 minutes, a positivesilver image will be formed. On the other hand, if the film is placed inthe color developing solution without being placed in the foggingdeveloping solution, a negative dye image will be produced in some casesand a positive dye image in others. If the color couplers used in thedeveloper are of the type described in Glass and Richey U. S. Patent2,507,154, a positive dye image will be produced and if the couplers areof the phenolic or naphtholic type, a negative dye image will beproduced.

In the short treatment in the selective fogging developer used in ourinvention, no visible image appears in the emulsion. The treatment ismainly one of preparation and conditioning for subsequent development.Presumably the selectively fogging developer creates development centerson the surface of the silver halide grains and these are moresusceptible to development in the active surface type developer used inthe second step, than the development centers created inside the grainsby the action of the earlier light exposure. When the emulsion issubjected to treatment in the selectively fogging developer, the grainsaifected by the light 6X posure are less susceptible to development inthe active surface type developer used in the second step, than thedevelopment centers created inside the grains by the action of earlierlight exposure. When the emulsion is subjected to the internal latentimage type is exposed to light under an image represented as having atransparent portion [2 and an opaque portion l3. This exposure producesan internal latent image at 14 in the emulsion layer I l.

, Treatment of the exposed element in the selectively fogging developerproduces a surface latent image at [5 in the portions of the layerswhich were not exposed without affecting the internal latent image at 14as shown in the second stage of the drawing.

A treatment of the element in an active color developer reduces thesurface latent image to a metallic silver and dye image it as shown inthe third stage of the drawing. The remaining silver halide and metallicsilver are then removed to leave the dye image I! in the portions of thelayer which were unexposed by the original exposure as shown in thefinal stage of Fig. l of the drawing.

Fig. 2 of the drawing illustrates a multi-layer material having asupport [3 with superposed emulsion layers [9, 20 and 2! coated thereon.Emulsion layer I9 is a red-sensitive internal latent image emulsioncontaining a color coupler capable of forming a cyan dye image. Emulsionlayer 20 is a green-sensitive internal latent image emulsion containingcolor coupler capable of producing a magenta dye image. Emulsion layer2| is a blue-sensitive internal latent image emulsion containing a colorcoupler capable of producing a yellow dye image. The usual yellow filterlayer 22 is present between emulsion layers 20 and 2| to prevent bluelight from exposing emulsion layers l9 and 20.

An ordinary surface type developer, that is, one which develops an imageonly on the surface 'of the grains of an internal latent image emulsionis the following.

Example 1 p-Hydroxyphenylglycine grams 10- Sodium canbonate, (crystals)-do Water to liter 1 Development time, 4 min. at 20 C.

An internal type developer, that is, one which develops an image insidethe grains of an :internal latent image emulsion is the following:

Example 2 Hydroquinone grams 15 Monomethyl-p-aminophenol sulfate do 15Sodium sulfite (anhyd) do 50 Potassium bromide do 10 Sodium hydroxide do25 Sodium thiosulfate (crystals) do 20 Water to liter 1 Developmenttime, 3 min. at 20 C.

A developer which produces a direct positive image on exposure anddevelopment of an internal latent image emulsion as described in axiom-eActive color developers which" may be used to fogging developer are asfollows:

Example 4 p-Amino diethylanillne HCI grams 2 Sodium sulfite (des.).-- -idor i 2 Sodium carbonate (anhyd) do 20 2,4-dichloro-l-naphthol -do 3Sodium hydroxide do 3 Water to 1iter 1 Example 5 ip-Aminodiethylanilirle FZCl grams 2 Sodium 'sulfite (des.) do 2 Sodiumcarbonate (anhyd) i do 20 JAcetoacet-2,5-dichloro .anilide Minded 3Sodium hydroxide headerv3 Water to s -i-- e liter 1 Eframple 6 p-Aminodiethylaniline HCl grams 2 Sodium sulfite (des.) do 2 Sodium carbonate(anhyd) do 20 p-Nitrophenyl acetonitrile do 3 :Sodiiiin hydroxide do 3Water to an. i r liter 1 In place of the couplers described above, anyof the customary color-forming compounds may be used.

Our invention will now be described by reference to the followingspecific example.

An emulsion such as that described in Davey and Knott U. S. application790,232 was coated on a support, dried and exposed on an Eastman IIbSensitometer (Jour. Soc. Motion Picture Engineers, vol. 17, 1931, page536). The exposed film was bathed for 15 seconds at 68 F. in thedeveloper of Example 3 in a shallow tray and after a '5-second rinse inrunning water was placed immediately in a tank containing one of thedevelopers of Examples i, 5 and 6 for a period of 10 minutes at 68 F.The three developers produced, respectively, silver and cyan, silver andyellow, and silver and magenta dye images. The silver images were thenbleached in the usual way and the undeveloped silver salts fixed out toleave dye images in the gelatin.

To prepare a multi-layer natural color dye image, a support was coatedwith successive layers of red-sensitive emulsion, green-sensitiveemulsion, yellow filter and blue-sensitive emulsion, all emulsions beingof the type described in Davey and Knott U. S. application 790,232. Thered-sensitive emulsion contained 5-(p-amyl phenoxy benzenesulfonamino-l-naphthol), the green-sensitive contained2-cyano-acetyl-5-(psec. amyl benzoylamino) coumarone and theblue-sensitive contained N amyl-p-benzoyl ace- .tamino benzenesulfonate. All couplers were dispersed in the emulsions as described inJelley and Vittum U. S. Patent 2,822,027, granted June 15, 1943.

The emulsions were exposed to a step tablet 6, andwere'then developedfor 15 minutes in L be following developer (Example 7): i

.Cyan;magenta, andyellow dye images were pro- 'ducedin thered-sensitive, green-sensitive and .blue sensitive layers, respectively,and the silver was" then converted toasoluble salt and removed by fixinginthe usual way.

It will be understood that the modifications included herein areillustrative only and that variations may be made incur process within,the

scope of the appended claims.

Weclaim: 1. The method oiuobtaining a direct positive :dye image in asilver halide emulsion layer, which comprises exposing to light rays towhich the emulsion is sensitive, a silver halide emulsion layer a testportion of which upon exposure to 'a light intensity scalefor a fixedtime between ,I/lOO'and 1 second andidevelopment for 3 minutes at20.C.'in thefollowing internal type de veloper:

Hydroquinone grams" l5 Monornethyl p-a1nino1: henol sulfate- .do '15Anhydrous sodiumsuliite s do 50 Potassiumbromide do 10 Sodium hydroxidedo. 25 Sodiumthiosulfate 1do 20 Water to liter 1 1 gives a maximumdensity at least 5 times the maximum density obtained when the equallyexposed silver halide emulsion is developed for 4 minutes at 20 C. inthe following surface de= veloper (I):

p-Hydroxyphenylglycine grams 10 Sodium carbonate (crystals) do Water toliter" 1 immersing the exposed emulsion layer in an aerial foggingdeveloper for about 15 seconds to l min ute, during which time novisible image is formed, then immersing said layer in an activesurfacetype developer containing a primary aromatic amino developingagent and a color coupler, for approximately 10 minutes during whichtime a positive dye image is formed in said layer.

2. The method of obtaining a direct positive dye image in a silverhalide emulsion layer, which comprises exposing to light rays to whichthe emulsion is sensitive, a silver halide emulsion layer a test portionof which upon exposure to a light intensity scale for a fixed timebetween 1/100 and 1 second and development for 3 minutes at 20 C. in thefollowing internal type developer:

Hydroquinone grams 15 Monomethyl-p-aminophenol sulfate do 15 Anhydroussodium sulfite do. 50 Potassium bromide do 10 Sodium hydroxide do 25Sodium thiosulfate do 20 Water to liter -1 gives a maximum density atleast 5 times the maximum density obtained when the equally exposedsilver halide emulsion is developed for 4 7 minutes at 20 C. in thefollowing surface developer (I) p-Hydroxyphenylglycine grams Sodiumcarbonate (crystals) do 100 Water to liter 1 immersing the exposed layerin an aerial fogging developer of the following composition for aboutseconds at 68 F.:

Hydroquinone grams 10 Sodium sulflte (des.) do 16 p-Formalydehyde do 4Sodium carbonate (anhyd.) do Benzotriazole do 0.4 Water to liter 1 thenimmersing said layer in an active surfacetype developer containing aprimary aromatic amino developing agent and a color coupler, for

7 approximately 10 minutes during which time a veloper:

Hydroquinone grams" 15 Monomethylp-aminophenol sulfate do 15 Anhydroussodium sulfite do 50 Potassium bromide do 10 Sodium hydroxide do 25Sodium thiosulfate do 20 Water to liter 1 gives a maximum density atleast 5 times the 8 maximum density obtained when the equally exposedsilver halide emulsion is developed for 4 minutes at 20 C. in thefollowing surface developer (I):

p-Hydroxyphenylglycine grams 10 Sodium carbonate (crystals) do Water toliter 1 immersing the exposed layer in an aerial fogging developer ofthe following composition for about 15 seconds at 68 F.:

Hydroquinone grams 10 Sodium sulflte (des.) do 16 p-Formaldehyde do 4Sodium carbonate (anhyd) do 25 Benzotriazole (10.... 0A Water to liter 1then immediately immersing said layer in the following active developerfor about 10 minutes at 68 F.:

p-Amino-diethylaniline HCi grams 2 Sodium sulflte (des.) do 2 Sodiumcarbonate (anhyd) do 20 p-Nitrophenyl acetonitrile do 3 Sodium hydroxidedo 3 Water to liter 1 thereby forming a positive magenta dye image insaid layer.

GEORGE EARLE FALLESEN. ROBERT ELIOT STAUFFER.

REFERENCES CITED The following references are of record in th file ofthis patent:

Wall: Photographic Emulsions," publ. 1929 by Amer. PhQt-.l?ub1. Co.,Boston; pages 52 and, 5.3..

1. THE METHOD OF OBTAINING A DIRECT POSITIVE DYE IMAGE IN SILVER HALIDEEMULSION LAYER, WHICH COMPRISES EXPOSING TO LIGHT RAYS TO WHICH THEEMULSION IS SENSITIVE, A SILVER HALIDE EMULSION LAYER A TEST PORTION OFWHICH UPON EXPOSURE TO A LIGHT INTENSITY SCALE FOR A FIXED TIME BETWEEN1/100 PART AND 1 SECOND AND DEVELOPMENT FOR 3 MINUTES AT 20* C. IN THEFOLLOWING INTERNAL TYPE DEVELOPER: